I am asking about some JavaScript library or API that I can integrate it in my winjs/HTML Windows store application. I would like to connect it with my data to render some awesome charts or pies etc. If someone have any library in mind it will be helpful for me.
Basically you can use any of the diverse Javascript graphing libraries out there. It will depend on what you want to achieve but here's a couple of libraries I found to be of very high quality:
In case charting is an important part of your app, this commercial library may be for you http://www.highcharts.com/
I also found this very extensive list which has even more charting libraries on it but didn't sift through it.